sys/vfs/hammer/hammer_prune.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/vfs/hammer/hammer_prune.c,v 1.14 2008/07/11 05:44:23 dillon Exp $
  35  */
  36
  37 #include "hammer.h"
  38
  39 /*
  40  * Iterate through the specified range of object ids and remove any
  41  * deleted records that fall entirely within a prune modulo.
  42  *
  43  * A reverse iteration is used to prevent overlapping records from being
  44  * created during the iteration due to alignments.  This also allows us
  45  * to adjust alignments without blowing up the B-Tree.
  46  */
  47 static int prune_should_delete(struct hammer_ioc_prune *prune,
  48                                hammer_btree_leaf_elm_t elm);
  49 static void prune_check_nlinks(hammer_cursor_t cursor,
  50                                hammer_btree_leaf_elm_t elm);
  51
  52 int
  53 hammer_ioc_prune(hammer_transaction_t trans, hammer_inode_t ip,
  54                  struct hammer_ioc_prune *prune)
  55 {
  56         struct hammer_cursor cursor;
  57         hammer_btree_leaf_elm_t elm;
  58         struct hammer_ioc_prune_elm *copy_elms;
  59         struct hammer_ioc_prune_elm *user_elms;
  60         int error;
  61         int isdir;
  62         int elm_array_size;
  63         int seq;
  64
  65         if (prune->nelms < 0 || prune->nelms > HAMMER_MAX_PRUNE_ELMS)
  66                 return(EINVAL);
  67         if ((prune->key_beg.localization | prune->key_end.localization) &
  68             HAMMER_LOCALIZE_PSEUDOFS_MASK) {
  69                 return(EINVAL);
  70         }
  71         if (prune->key_beg.localization > prune->key_end.localization)
  72                 return(EINVAL);
  73         if (prune->key_beg.localization == prune->key_end.localization) {
  74                 if (prune->key_beg.obj_id > prune->key_end.obj_id)
  75                         return(EINVAL);
  76                 /* key-space limitations - no check needed */
  77         }
  78         if ((prune->head.flags & HAMMER_IOC_PRUNE_ALL) && prune->nelms)
  79                 return(EINVAL);
  80
  81         prune->key_cur.localization = prune->key_end.localization +
  82                                       ip->obj_localization;
  83         prune->key_cur.obj_id = prune->key_end.obj_id;
  84         prune->key_cur.key = HAMMER_MAX_KEY;
  85
  86         /*
  87          * Copy element array from userland
  88          */
  89         elm_array_size = sizeof(*copy_elms) * prune->nelms;
  90         user_elms = prune->elms;
  91         copy_elms = kmalloc(elm_array_size, M_TEMP, M_WAITOK);
  92         if ((error = copyin(user_elms, copy_elms, elm_array_size)) != 0)
  93                 goto failed;
  94         prune->elms = copy_elms;
  95
  96         seq = trans->hmp->flusher.act;
  97
  98         /*
  99          * Scan backwards.  Retries typically occur if a deadlock is detected.
 100          */
 101 retry:
 102         error = hammer_init_cursor(trans, &cursor, NULL, NULL);
 103         if (error) {
 104                 hammer_done_cursor(&cursor);
 105                 goto failed;
 106         }
 107         cursor.key_beg.localization = prune->key_beg.localization +
 108                                       ip->obj_localization;
 109         cursor.key_beg.obj_id = prune->key_beg.obj_id;
 110         cursor.key_beg.key = HAMMER_MIN_KEY;
 111         cursor.key_beg.create_tid = 1;
 112         cursor.key_beg.delete_tid = 0;
 113         cursor.key_beg.rec_type = HAMMER_MIN_RECTYPE;
 114         cursor.key_beg.obj_type = 0;
 115
 116         cursor.key_end.localization = prune->key_cur.localization;
 117         cursor.key_end.obj_id = prune->key_cur.obj_id;
 118         cursor.key_end.key = prune->key_cur.key;
 119         cursor.key_end.create_tid = HAMMER_MAX_TID - 1;
 120         cursor.key_end.delete_tid = 0;
 121         cursor.key_end.rec_type = HAMMER_MAX_RECTYPE;
 122         cursor.key_end.obj_type = 0;
 123
 124         cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;
 125         cursor.flags |= HAMMER_CURSOR_BACKEND;
 126
 127         /*
 128          * This flag allows the B-Tree code to clean up loose ends.
 129          */
 130         cursor.flags |= HAMMER_CURSOR_PRUNING;
 131
 132         error = hammer_btree_last(&cursor);
 133
 134         while (error == 0) {
 135                 /*
 136                  * Check for work
 137                  */
 138                 elm = &cursor.node->ondisk->elms[cursor.index].leaf;
 139                 prune->key_cur = elm->base;
 140
 141                 /*
 142                  * Yield to more important tasks
 143                  */
 144                 if ((error = hammer_signal_check(trans->hmp)) != 0)
 145                         break;
 146
 147                 if (prune->stat_oldest_tid > elm->base.create_tid)
 148                         prune->stat_oldest_tid = elm->base.create_tid;
 149
 150                 if (hammer_debug_general & 0x0200) {
 151                         kprintf("check %016llx %016llx cre=%016llx del=%016llx\n",
 152                                         elm->base.obj_id,
 153                                         elm->base.key,
 154                                         elm->base.create_tid,
 155                                         elm->base.delete_tid);
 156                 }
 157
 158                 if (prune_should_delete(prune, elm)) {
 159                         if (hammer_debug_general & 0x0200) {
 160                                 kprintf("check %016llx %016llx: DELETE\n",
 161                                         elm->base.obj_id, elm->base.key);
 162                         }
 163
 164                         /*
 165                          * NOTE: This can return EDEADLK
 166                          *
 167                          * Acquiring the sync lock guarantees that the
 168                          * operation will not cross a synchronization
 169                          * boundary (see the flusher).
 170                          */
 171                         isdir = (elm->base.rec_type == HAMMER_RECTYPE_DIRENTRY);
 172
 173                         hammer_sync_lock_sh(trans);
 174                         error = hammer_delete_at_cursor(&cursor,
 175                                                         HAMMER_DELETE_DESTROY,
 176                                                         &prune->stat_bytes);
 177                         hammer_sync_unlock(trans);
 178                         if (error)
 179                                 break;
 180
 181                         if (isdir)
 182                                 ++prune->stat_dirrecords;
 183                         else
 184                                 ++prune->stat_rawrecords;
 185
 186                         /*
 187                          * The current record might now be the one after
 188                          * the one we deleted, set ATEDISK to force us
 189                          * to skip it (since we are iterating backwards).
 190                          */
 191                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 192                 } else {
 193                         /*
 194                          * Nothing to delete, but we may have to check other
 195                          * things.
 196                          */
 197                         prune_check_nlinks(&cursor, elm);
 198                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 199                         if (hammer_debug_general & 0x0100) {
 200                                 kprintf("check %016llx %016llx: SKIP\n",
 201                                         elm->base.obj_id, elm->base.key);
 202                         }
 203                 }
 204                 ++prune->stat_scanrecords;
 205
 206                 if (hammer_flusher_meta_halflimit(trans->hmp) ||
 207                     hammer_flusher_undo_exhausted(trans, 1)) {
 208                         hammer_unlock_cursor(&cursor, 0);
 209                         hammer_flusher_wait(trans->hmp, seq);
 210                         hammer_lock_cursor(&cursor, 0);
 211                         seq = hammer_flusher_async(trans->hmp);
 212                 }
 213                 error = hammer_btree_iterate_reverse(&cursor);
 214         }
 215         if (error == ENOENT)
 216                 error = 0;
 217         hammer_done_cursor(&cursor);
 218         if (error == EDEADLK)
 219                 goto retry;
 220         if (error == EINTR) {
 221                 prune->head.flags |= HAMMER_IOC_HEAD_INTR;
 222                 error = 0;
 223         }
 224 failed:
 225         prune->key_cur.localization &= HAMMER_LOCALIZE_MASK;
 226         prune->elms = user_elms;
 227         kfree(copy_elms, M_TEMP);
 228         return(error);
 229 }
 230
 231 /*
 232  * Check pruning list.  The list must be sorted in descending order.
 233  *
 234  * Return non-zero if the record should be deleted.
 235  */
 236 static int
 237 prune_should_delete(struct hammer_ioc_prune *prune, hammer_btree_leaf_elm_t elm)
 238 {
 239         struct hammer_ioc_prune_elm *scan;
 240         int i;
 241
 242         /*
 243          * If pruning everything remove all records with a non-zero
 244          * delete_tid.
 245          */
 246         if (prune->head.flags & HAMMER_IOC_PRUNE_ALL) {
 247                 if (elm->base.delete_tid != 0)
 248                         return(1);
 249                 return(0);
 250         }
 251
 252         for (i = 0; i < prune->nelms; ++i) {
 253                 scan = &prune->elms[i];
 254
 255                 /*
 256                  * Check for loop termination.
 257                  */
 258                 if (elm->base.create_tid >= scan->end_tid ||
 259                     elm->base.delete_tid > scan->end_tid) {
 260                         break;
 261                 }
 262
 263                 /*
 264                  * Determine if we can delete the record.
 265                  */
 266                 if (elm->base.delete_tid &&
 267                     elm->base.create_tid >= scan->beg_tid &&
 268                     elm->base.delete_tid <= scan->end_tid &&
 269                     (elm->base.create_tid - scan->beg_tid) / scan->mod_tid ==
 270                     (elm->base.delete_tid - scan->beg_tid) / scan->mod_tid) {
 271                         return(1);
 272                 }
 273         }
 274         return(0);
 275 }
 276
 277 /*
 278  * Dangling inodes can occur if processes are holding open descriptors on
 279  * deleted files as-of when a machine crashes.  When we find one simply
 280  * acquire the inode and release it.  The inode handling code will then
 281  * do the right thing.
 282  */
 283 static
 284 void
 285 prune_check_nlinks(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm)
 286 {
 287         hammer_inode_t ip;
 288         int error;
 289
 290         if (elm->base.rec_type != HAMMER_RECTYPE_INODE)
 291                 return;
 292         if (elm->base.delete_tid != 0)
 293                 return;
 294         if (hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA))
 295                 return;
 296         if (cursor->data->inode.nlinks)
 297                 return;
 298         hammer_cursor_downgrade(cursor);
 299         ip = hammer_get_inode(cursor->trans, NULL, elm->base.obj_id,
 300                       HAMMER_MAX_TID,
 301                       elm->base.localization & HAMMER_LOCALIZE_PSEUDOFS_MASK,
 302                       0, &error);
 303         if (ip) {
 304                 kprintf("pruning disconnected inode %016llx\n",
 305                         elm->base.obj_id);
 306                 hammer_rel_inode(ip, 0);
 307         } else {
 308                 kprintf("unable to prune disconnected inode %016llx\n",
 309                         elm->base.obj_id);
 310         }
 311 }
 312
 313 #if 0
 314
 315 /*
 316  * NOTE: THIS CODE HAS BEEN REMOVED!  Pruning no longer attempts to realign
 317  *       adjacent records because it seriously interferes with every
 318  *       mirroring algorithm I could come up with.
 319  *
 320  *       This means that historical accesses beyond the first snapshot
 321  *       softlink should be on snapshot boundaries only.  Historical
 322  *       accesses from "now" to the first snapshot softlink continue to
 323  *       be fine-grained.
 324  *
 325  * NOTE: It also looks like there's a bug in the removed code.  It is believed
 326  *       that create_tid can sometimes get set to 0xffffffffffffffff.  Just as
 327  *       well we no longer try to do this fancy shit.  Probably the attempt to
 328  *       correct the rhb is blowing up the cursor's indexing or addressing mapping.
 329  *
 330  * Align the record to cover any gaps created through the deletion of
 331  * records within the pruning space.  If we were to just delete the records
 332  * there would be gaps which in turn would cause a snapshot that is NOT on
 333  * a pruning boundary to appear corrupt to the user.  Forcing alignment
 334  * of the create_tid and delete_tid for retained records 'reconnects'
 335  * the previously contiguous space, making it contiguous again after the
 336  * deletions.
 337  *
 338  * The use of a reverse iteration allows us to safely align the records and
 339  * related elements without creating temporary overlaps.  XXX we should
 340  * add ordering dependancies for record buffers to guarantee consistency
 341  * during recovery.
 342  */
 343 static int
 344 realign_prune(struct hammer_ioc_prune *prune,
 345               hammer_cursor_t cursor, int realign_cre, int realign_del)
 346 {
 347         struct hammer_ioc_prune_elm *scan;
 348         hammer_btree_elm_t elm;
 349         hammer_tid_t delta;
 350         hammer_tid_t tid;
 351         int error;
 352
 353         hammer_cursor_downgrade(cursor);
 354
 355         elm = &cursor->node->ondisk->elms[cursor->index];
 356         ++prune->stat_realignments;
 357
 358         /*
 359          * Align the create_tid.  By doing a reverse iteration we guarantee
 360          * that all records after our current record have already been
 361          * aligned, allowing us to safely correct the right-hand-boundary
 362          * (because no record to our right is otherwise exactly matching
 363          * will have a create_tid to the left of our aligned create_tid).
 364          */
 365         error = 0;
 366         if (realign_cre >= 0) {
 367                 scan = &prune->elms[realign_cre];
 368
 369                 delta = (elm->leaf.base.create_tid - scan->beg_tid) %
 370                         scan->mod_tid;
 371                 if (delta) {
 372                         tid = elm->leaf.base.create_tid - delta + scan->mod_tid;
 373
 374                         /* can EDEADLK */
 375                         error = hammer_btree_correct_rhb(cursor, tid + 1);
 376                         if (error == 0) {
 377                                 error = hammer_btree_extract(cursor,
 378                                                      HAMMER_CURSOR_GET_LEAF);
 379                         }
 380                         if (error == 0) {
 381                                 /* can EDEADLK */
 382                                 error = hammer_cursor_upgrade(cursor);
 383                         }
 384                         if (error == 0) {
 385                                 hammer_modify_node(cursor->trans, cursor->node,
 386                                             &elm->leaf.base.create_tid,
 387                                             sizeof(elm->leaf.base.create_tid));
 388                                 elm->leaf.base.create_tid = tid;
 389                                 hammer_modify_node_done(cursor->node);
 390                         }
 391                 }
 392         }
 393
 394         /*
 395          * Align the delete_tid.  This only occurs if the record is historical
 396          * was deleted at some point.  Realigning the delete_tid does not
 397          * move the record within the B-Tree but may cause it to temporarily
 398          * overlap a record that has not yet been pruned.
 399          */
 400         if (error == 0 && realign_del >= 0) {
 401                 scan = &prune->elms[realign_del];
 402
 403                 delta = (elm->leaf.base.delete_tid - scan->beg_tid) %
 404                         scan->mod_tid;
 405                 if (delta) {
 406                         error = hammer_btree_extract(cursor,
 407                                                      HAMMER_CURSOR_GET_LEAF);
 408                         if (error == 0) {
 409                                 hammer_modify_node(cursor->trans, cursor->node,
 410                                             &elm->leaf.base.delete_tid,
 411                                             sizeof(elm->leaf.base.delete_tid));
 412                                 elm->leaf.base.delete_tid =
 413                                             elm->leaf.base.delete_tid -
 414                                             delta + scan->mod_tid;
 415                                 hammer_modify_node_done(cursor->node);
 416                         }
 417                 }
 418         }
 419         return (error);
 420 }
 421
 422 #endif